Gee, the same thing happened to me.
Just flew LGA-MCO/MCO-JFK recently with B6. Nothing posted so far.
Reached out to B6 and got this:
"Hello again,
In order to receive KrisFlyer Miles for your JetBlue flights, you'll need to contact Singapore
Airlines to make a retroactive request. They can be reached at 1-800-742-3333."
Absolute BS since I put my SQKF# into the booking. Appears on the itinerary as well.
Will request from SQ and see where that takes me.